Brake Valve
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Freshman User
Joined: Nov 2006
Posts: 26
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From: Texas
Brake Valve
I have a 78 F-150 with brake problems.I have replaced the booster,master cylinder,calipers,hoses,and wheel cylinders.I have bled the brakes about ten times.Now it will stop but the back brakes lockup and it doesent feel like the front is stopping at all. A friend told me it sounds like the proportioning valve the only one i found is 199.99 and I was wanting to know if anyone had taken one apart.I thought there might be some trash in it and was going to try to clean it out but I dont know how it comes apart or what to expect once I get in there. Thanks for any help.
New User
Joined: Jan 2008
Posts: 0
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Welcome to FTE.
You've come to the right place
Have a look here. You'll be pleasantly surprised.
http://www.inlinetube.com/Prop%20Valves/VFL101.htm
You've come to the right place
Have a look here. You'll be pleasantly surprised.
http://www.inlinetube.com/Prop%20Valves/VFL101.htm
Senior User
Joined: Jan 2004
Posts: 117
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From: Southern Minnesota
i own a pile of old ford trucks and rarly have troubles with the proportioning valve i have heard or people talk about taking them apart and cleaning them so it wold be worth a shot cheaper than $200
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Freshman User
Joined: Nov 2006
Posts: 26
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From: Texas
Thank you for the replys. I checked out that site and think I am going to take the valve off in the next couple of days to see whats going on. The truck sat for about a year after that the brakes were bad.If I cant get mine working I will buy a new one.Has anyone used any of those parts before?
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Brake fluid is hygroscopic and without the constant heating from brake applications to drive out the moisture it will corrode everything inside the brake system. You will probably find the valve is seized up with rust etc. It may not be repairable. Water vapor passes thru rubber and seal points and into the system. One of the absolutely worst things you can do to a vehicle is let it sit unused.
Posting Guru
Joined: Sep 2003
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From: lino lakes, mn
look at the p-valve see if the valve is centered there is a rubber cap at one end sometimes when you bleed the brakes the pin won't recenter you could try putting someone in the cab pump the hold the brakes the crack loose the lines at the master do the one for the front brakes first see if this recenters the p-valve. If you look in the manual they have a little clip that they use to hold the valve out when bleeding the brakes
New User
Joined: Sep 2006
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I recently bought and used a porpotioning valve from inline. Everything works fine for me...I did change every componet in the brake system though.
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Posting Guru
Joined: Mar 2006
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From: The City
well, with my last truck I had, it had the same problem, rears would not bleed @ all, the brake light stayed on and stopping was much a planned event, emergency stops or quick stops were handled by either turning the truck off, or using Park, or e brake(which didnt work very well either), I tried cleaning and rebuilding mine also but no such good luck, didnt help a lot
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Freshman User
Joined: Sep 2006
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I have a 77 f250 Highboy and had the same problems. The rear liked to try and pass you on a hard stop. I've replaced almost everything except all the lines. I started with the MC/Booster because my booster went out. Then it still didn't stop correctly so I replaced the proportioning valve as well. Got it all bled out and it worked correctly for a short while but it's back to wanting to pull to the left on the front end when I stop hard. So I don't know exactly how much replacing the P-valve did for me.
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Freshman User
Joined: Nov 2006
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From: Texas
Update
I decided to go with a adjustable proportioning valve from Jegs. I removed the old valve and couldn't see much wrong with it so i decided to put a little air to the inlet lines to see what happend. The back blew through fine but when I went to the front it started to blow through then the pin sticking out the end came out and stopped the flow.So I thought that must be the reason why 2 year old front pads still look new.I replaced the valve,bled the brakes and it would stop.Not throw you through the windshield but stop.Drove around, came home,cleaned up got back in the truck the pedal was on the floor. I can't find any drips but I must be getting air into the system. The only thing I can think is a line has a small hole in it so my next task is replace all the lines.Has anyone had a cracked line that doesn't leak fluid?
I decided to go with a adjustable proportioning valve from Jegs. I removed the old valve and couldn't see much wrong with it so i decided to put a little air to the inlet lines to see what happend. The back blew through fine but when I went to the front it started to blow through then the pin sticking out the end came out and stopped the flow.So I thought that must be the reason why 2 year old front pads still look new.I replaced the valve,bled the brakes and it would stop.Not throw you through the windshield but stop.Drove around, came home,cleaned up got back in the truck the pedal was on the floor. I can't find any drips but I must be getting air into the system. The only thing I can think is a line has a small hole in it so my next task is replace all the lines.Has anyone had a cracked line that doesn't leak fluid?
Senior User
Joined: Oct 2004
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From: Medina, Ohio
Hi, even tho you put a new master and booster on it they still might be bad. I would check that first. A line with a crack or hole will show with the pressure you get from pushing on the pedel. Air will not go in the hole or crack that fast to make your pedel go down. Erv
Posting Guru
Joined: Mar 2006
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From: The City
dang, yesterday morn I had my r/r wheel cyl go out on me, must be bad times 4 brakes, i gravity bled mine and they feel great, instructions: how 2 gravity bleed brakes, 1: remove cover from master cylinder, 2: open either both fronts or both backs(or all, depends on what part of the system u just repaired) 3 watch for steady fluid drip from bleeder screws on both sides, if no bubbles r present and fluid is slowly, but steadily coming out, tighten bleeder screws
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Freshman User
Joined: Nov 2006
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From: Texas
found problem
I was under the truck bleeding the 1000th gallon of fluid and saw a leak on the new valve. Thought it must be loose but it was tight so i pulled the line off to check my flare and see what was going on. The flare looked ok but I am not a flare machine so I decided to cut a piece of line about 3 inches long and smash the end with a hammer to see if i could stop the leak with a store bought flare. Put fluid in the master cylinder and the leak was still bad. Anyway a friend of mine wants to just run a tee on the front brakes and a small valve to turn down pressure in the back.Has anyone ever run anything without a prop valve? A guy at the parts place here said that it would work but the lines have to be the same length and to put about 3 or 4 loops in them so the lines dont blow out. Any advice?
Postmaster
Joined: Oct 2005
Posts: 3,034
Likes: 1
From: NJ
They have a proportioning valve for a reason and I wouldn't try what your friend is suggesting. Are you sure your flare is good? Did you do this flare yourself? Sure line was tight? Maybe you got a defective valve. I would not bypass the valve. Don't do bootleg repairs on something as important as your brakes. Fix it the right way.
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Freshman User
Joined: Nov 2006
Posts: 26
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From: Texas
I did the flare myself thats why I crimped the small line and put it on to see if a factory flare would fix my problem but it didn't.I was also worried about the tee but I am almost willing to try anything at this point.